Carbon coated high luster materials

ABSTRACT

A platy pigment substrate having a carbon-containing coating thereon is provided wherein the coating comprises a pyrolyzed carbon-containing ionic species. The products of the present invention may be used in any application where pearlescent pigments have been used heretofore including but not limited to automotive and industrial paint applications.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation in part of Provisional ApplicationU.S. Ser. No. 60/471,636, filed May 19, 2003.

BACKGROUND OF THE INVENTION

Effect pigments, also known as nacreous pigments and pearlescentpigments, are lustrous specialty chemical products which are widely usedin a variety of high-end applications such as automotive finishes. Oneof the attributes of the effect pigments is that they can generate arange of optical effects depending on the angle at which they areviewed.

In a number of applications, the effect materials have a lesser degreeof hiding power than desired. One method which has been used to addressthis problem is to incorporate a carbonaceous material within theformulation. Users, however, would prefer that the carbon additive besupplied as a part of the effect material-rather than separately to beadded by the user prior to application.

Effect pigments are often based on platelet shaped particles. Becausethe optical effect is the result of multiple reflections andtransmission of light, it is desirable to provide particles which willalign in the medium in which they are found and to optimize the desiredeffect. The presence of either misaligned particles or particles of anadditive, or both, interferes with this objective and diminishes theoptical effect of the pigment. It is therefore desirable for the carbonadditive being used for increased hiding to be somehow bound to theplatelets rather than present as part of a physical mixture.

The formation of a carbon coating on a platy substrate is known. U.S.Pat. No. 3,107,173 discloses a coating of translucent micaceous flakesubstrates with a thin, adherent, substantially continuous, translucentlayer of carbon. The carbon layer is formed on the flake substrates bypyrolyzing a carbon-containing material in contact with the flakesubstrate in an inert atmosphere.

U.S. Pat. No. 5,702,518 discloses a gold-colored pigment in which asubstrate coated with metal oxides is characterized by a first layer oftitanium dioxide doped with carbon obtained by thermal decomposition oforganic colloidal particles and a second layer which is ferric oxide.

U.S. Pat. No. 5,356,471 teaches the formation of a platelet-likesubstrate coated with metal oxides in which a black surface color isachieved by reacting the platelet-like substrate with a silane followedby pyrolysis.

According to U.S. Pat. No. 5,286,291, prior art processes where carbonblack was formed by pyrolysis of organic compounds or by mixing asubstrate with carbon black followed by hydrolyzing a metal salt,results in producing pigments with insufficient wear resistance or thedeposition of the carbon black on the pigment is in agglomerated form sothat the pigments do not have good hiding power. To overcome thisdisadvantage, the patent teaches coating the platelet-like substrateswith carbon black particles, and optionally a metal oxide, and beingdoped with an anionic or cationic and nonionic surfactants and anorganosilane compound so as to fix the carbon black on the substrate andimprove the abrasion and bleeding resistance of the pigment. Theresulting product is calcined.

U.S. Pat. No. 5,271,771 teaches the formation of carbon-containingplate-like pigments by pyrolysis of carbon containing compounds in thepresence of either plate-like metal oxides or metal oxide mixtures orsubstrates coated with titanium dioxide and at least one further metaloxide under conditions in which the metal of the metal oxide is reduced.The metal oxide or metal oxide mixtures can include Fe₂O₃.

U.S. Pat. No. 6,436,538 teaches effect pigments which are a collectionof platelet-like particles coated with a nitrogen-doped carbon coating.This is made by adding a carbon and nitrogen containing polymer (ormonomers to form the same) to the particles suspended in a liquid,coating the polymer on the surface of the particles, optionally in thepresence of a surface modifier such as a neutral, cationic, anionic oramphoteric surfactant, reactive metal compound or polar polymer, andthen pyrolyzing the particles in a gaseous atmosphere.

The object of the present invention is to provide a new process forforming carbon-containing, highly lustrous materials and to theresulting materials so produced. This and other objects of the inventionwill become apparent to those skilled in this art from the followingdetailed description.

SUMMARY OF THE INVENTION

This invention provides a pigment comprising a platy pigment substratehaving a coating thereon wherein the coating comprises acarbon-containing ionic species which is treated to form a uniform ornon-uniform layer of carbon on the substrate.

This invention also provides a pigment comprising an effect pigmentsubstrate having a carbon-containing coating thereon wherein the coatingcomprises a pyrolyzed carbon-containing ionic species.

This invention also provides a pigment comprising an effect pigmentsubstrate having a thin carbon-containing coating on the surfacethereof, wherein the carbon in the coating is less than about 5% of thetotal weight and the carbon-containing coating is such that the hidingpower of the carbon- coated pigment is greater than that of thesubstrate.

The invention also relates to the method of forming a carbon-coated highluster pigment in which an effect pigment (substrate) is coated withalternating layers of carbon-containing cationic and anionic species andthe coating is then pyrolyzed or otherwise treated to yield a carboncoating on the substrate.

This invention also provides a method of forming a carbon-coated highluster platy pigment which comprises pyrolyzing a coated pigmentcomprising a platy pigment substrate having one chargedcarbon-containing ionic species or alternating layers of oppositelycharged carbon-containing ionic species thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the influence of carbon content on the intensity of aUV-Vis band at approximately 425 nm for a first carbon-coated effectpigment.

FIG. 2 shows the influence of carbon content on spectral peak positionfor the first carbon-coated effect pigment.

FIG. 3 shows the UV-Vis spectra for a carbon-coated and uncoated firsteffect pigment.

FIG. 4 shows the UV-Vis spectrum of a physical mixture of carbon blackwith a second effect pigment, that of its carbon-coated analog, and theeffect pigment itself.

FIG. 5 shows the UV-Vis spectra for the second carbon-coated effectpigment with varying carbon levels.

FIG. 6 shows the influence of carbon content on the intensity of theUV-Vis band at approximately 600 nm for the second carbon-coated effectpigment.

FIG. 7 plots the intensity difference between the UV-Vis features atapproximately 600 nm and 490 nm for the second carbon-coated effectpigment.

FIG. 8 shows the change in UV peak width relative to carbon content forthe second carbon-coated effect pigment.

FIG. 9 plots the UV band position as a function of carbon content forthe second carbon-coated effect pigment.

FIG. 10 shows the UV-Vis spectra for a third carbon-coated effectpigment. FIG. 11 shows the UV-Vis spectra for a fourth carbon-coatedeffect pigment.

FIG. 12 shows the UV-Vis spectra for a fifth carbon-coated effectpigment.

DESCRIPTION OF THE INVENTION

The substrates which can be employed in the present invention can be anyknown platy pigment, preferably an effect pigment, which is optionallycoated with a wide variety of inorganic coloring agents.

The substrate to be treated can also be any platy material such as micaflakes, titanium dioxide, sericite, kaolin, gypsum, bismuth oxychloride,glass, platy iron oxide, platy aluminum oxide, platy silicon dioxide,synthetic mica and the like. Suitable mixtures of platy substrates mayalso be used.

Usable coated platelets are exemplified by titanium dioxide-, zirconiumdioxide- and/or iron oxide-coated mica and/or glass. The substrate mayalso be an optically variable pearlescent or effect pigment.

Preferred are the well-known metal-oxide-coated mica or glass effectpigments. The metal oxide-coated substrate nacreous pigments are wellknown and are exemplified by titanium dioxide- and/or iron oxide-coatedmica. Such pigments are described, inter alia, in U.S. Pat. No.3,437,513; 3,418,146; 3,087,828; and 4,083,099. A preferred nacreouspigment is titanium dioxide-coated mica. The mica flake substratesgenerally have a length of about 1 to about 75 microns, preferably about5 to about 35 microns, and a thickness between about 0.3 and about 3microns, but both larger and smaller dimensions can also be employed.Usually, the titanium dioxide or other metal oxide will be coated on thesubstrate surface to a thickness of about 20 to about 350 nanometers orsuch that it is about 50 to 500 mg/m², depending on the specific surfacearea of the substrate in m²/g. Depending on the thickness of the metaloxide coating, the pigments can exhibit interference or reflectioncolors of blue, green, yellow, red, etc.

The substrate, which forms the core of the final product, is thenprovided with alternating layers of charged carbon-containing ionicspecies. The carbon-containing cationic and anionic species can be anyorganic compound containing a carbon group, preferably, a plurality ofcarbon groups and which has a positive or negative charge under reactionconditions. Also preferred are organic oligomers and polymers having apositve or negative charge under reaction conditions. In most cases thecompounds, oligomers or polymers will contain a counter ion. The processused is similar to that taught in U.S. Pat. No. 5,152,835, thedisclosure of which is incorporated herein by reference, where acomposite titania-calcined kaolin opacifying pigment was prepared byintroducing at least one anionic polymer into a pigment slurry to whicha cationic polyelectrolyte was introduced using a strongly alkaline pHabove 9.

The charge on the core particles is used in the present invention tofacilitate the adsorption of an ionic species on the surface of theparticles. The ionic species can be either anionic or cationic. In oneprocess, a solution or dispersion of the desired ionic species is firstprepared. The pigment particles are then added, with mixing, to thesolution or dispersion. Some pigments may require prior wetting, with awetting agent, before adding the pigment to the solution or dispersion.That is, the core pigment particle dispersion is formed, with either ananionic or cationic ionic species which imparts to the particle a chargeof opposite sign on that of the core particle.

In making the core pigment particle dispersion, an aqueous mediumusually is employed. The charged carbon-containing ionic species such asthe cationic or anionic polymers, are those that ionize in the medium.The charged species are also those that form, on ionization, anions orcations that are strongly adsorbed onto the surface of the pigments. Asa result of this adsorption, the particles become positively ornegatively charged, depending on the cationic or anionic nature,respectively, of the charge reversing agents. The ions are localized atthe surface of the particles. The magnitude of the charge on a particledepends upon the number of ions adsorbed onto each particle, and uponthe charge of each ion.

Other descriptions of electrostatic deposition of one material ontoanother by utilizing charge reversal can be found in Valtchev andMintova, Microporous and Mesoporous Materials, 433 (2001), Wang et al.,Chemical Communications, 2161 (2000) and Millward et al. ChemicalCommunications, 1994, (2002).

Anionic polymers which can be used as the charged carbon-containgspecies of the present invention include low, medium, and high molecularweight polymers, for example in the range of about 2,000 to about500,000. Examples of polymeric species capable of forming largepolyanions, when ionized, are well known. A preferred polymeric speciesis a water-soluble vinyl polymer, or an alkali metal or ammonium saltthereof, or an alkali metal or ammonium salt of polysilicic acid.Specific examples include poly (acrylic) acids, poly (methacrylic)acids, substituted poly (acrylic acid), substituted poly (methacrylicacid), or an alkali metal or an ammonium salt of any of these acids. Onecommercially available anionic species is sodium polyacrylate.Poly(sodium 4-styrene sulfonate) is available from National Starch andChemical under the trademark “Flexan 130”.

Examples of suitable cationic polymers useful in the present inventionare disclosed in U.S. Pat. No. 5,006,574. One useful water-solublecationic polymeric material is an alkyl diallyl quaternary ammoniumpolymer salt. This cationic polymer is characterized by a high densityof positive charge. Preferably, the polymer does not have negativegroups such as carboxyl or carbonyl groups.

U.S. Pat. No. 5,006,574 also discloses other quaternary ammoniumcationic polymers obtained by copolymerizing an aliphatic secondaryamine with epichlorohydrin. Still other water-soluble cationicpolyelectrolytes are poly (quaternary ammonium) polyester salts thatcontain quaternary nitrogen in a polymeric backbone and are chainextended by the groups. They are prepared from water-soluble poly(quaternary ammonium salts) containing pendant hydroxyl groups andbi-functionally reactive chain extending agents. Such polyelectrolytesare prepared by treating N,N,N′,N-tetraalkylhydroxyalkylene diamine andan organic dihalide such as dihaloalkane or dihaloether with an epoxyhaloalkane. Other water-soluble cationic polyelectrolytes arepolyamines, such as for instance polyallylamine hydrochloride, andalkylphosphonium salts.

An example of the adsorption of a cationic water-soluble polymer onto apigment particle from an aqueous dispersion is described in U.S. Pat.No. 4,874,466 for a process of forming an improved paper making fillercomposition. The polymer comprises at least 50 weight percent ofrepeating units consisting of an alkyl and/or aryl quaternary ammoniumsalt moiety, wherein the alkyl or aryl moieties may be substituted withhydroxy, amine or halide. Polyaluminum chloride and mixtures thereofwith the alkyl and/or aryl ammonium salt polymers are also disclosed asuseful cationic polymers. The disclosure of U.S. Pat. No. 4,874,466 isalso incorporated by reference herein.

Cationic polymeric species are also commercially available. For instancea cationic oligomer is marketed by Calgon Corp. under the trademark“CALGON 261” and another marketed by Nalco Chemical Co. under thetrademark “NALCO 7607.”

After the substrate is coated with the carbon-containing ionic speciessuch as a charged polymer, either cationic or anionic, it can be washedand optionally dried and then the procedure repeated with, for example,a polymer of opposite charge. Alternatively, the filtration (separation)and washing steps between treatments can be eliminated. In the latterprocedure, after a suitable deposition time has elapsed for the firstpolymer, the second polymer is added with no intermediate filtration.The alternate coating steps can be repeated as many times as desired andthe final coating can be cationic or anionic, as desired. At any timeduring the coating a plurality of times with a cationic or anionicagent, the identity of either (or both) particular agent can be changedif desired.

When the deposition process is completed, the sample is treated to forma carbonized coating on the substrate. For example, the sample can bepyrolyzed by thermal treatment in a controlled atmosphere. Thetemperature of the thermal treatment, the duration of the treatment andthe atmosphere of the thermal treatment will vary depending on theparticular compounds or polymers used to coat the substrate and on thesubstrate itself. In general, the treatment gas is nitrogen but othergases or gas mixtures such as carbon dioxide and nitrogen can also beused. The use of a nitrogen stream containing at least about 0.1% CO₂ isexemplified. The temperature employed is usually at least about 300° C.,preferably at least about 600° C. and the heating is usually conductedfor a duration ranging from 10 minutes to 10 hours, more typicallyranging from 30 minutes to 2 hours at the final temperature. The maximumusable temperature is usually established by the stability of the corematerial which has been coated. The appearance of some effect pigments,for instance, iron oxide-coated mica, may be effected by the pyrolysisand the particular parameters of the treatment are selected to take thatinto account.

Scanning electron microscopy imaging of a carbon-coated effect pigmentmade in accordance with the present invention in which the effectpigment coated was a titanium dioxide-coated mica looked the same as theeffect pigment prior to carbon coating. Nevertheless, the carbon-coatedeffect pigment exhibited enhanced hiding power compared to the effectpigment prior to coating either alone or admixed with carbon black atthe same carbon level, and the three materials had different UV-visiblespectra.

Since the coating after pyrolysis is derived from a carbon-containingmaterial, the presence of carbon is expected and that has been confirmedby elemental analysis. XPS results indicated that the carbon coating isclearly observed while elements present in the effect material which hasbeen coated can still be detected. The carbon coating realized istherefore very thin.

A wide range of carbon contents can be achieved by varying the number ofcoatings of the charge reversing agents. The carbon content can also bevaried by varying the pyrolysis conditions. This flexibility in carboncontent is important to achieve a range of optical properties.

The overall nitrogen content in the product of the invention can be solow that it is not accurately detected by routinecarbon-hydrogen-nitrogen analysis. By using analysis techniques with avery low detection limit such as 1 ppm, a nitrogen content lower thanabout 1 wt. % of the carbon coating has been observed after subtractingthe nitrogen content of the effect pigment coated. Nitrogen contentsbelow 4 wt. % of the carbon coating are also useful.

After the substrate has been coated with the desired ionic polymerspecies, washed and dried, it has been found that acidification of thepolymer surface prior to pyrolysis is a useful distinguishing feature.One consequence of acidification is that pyrolysis can be achieved withnitrogen in one step without the need for CO₂. This may be desirable interms of processing costs and requirements. In addition, there may alsobe important consequences in terms of the properties of the resultantcarbon-coated pigment compared with a pigment formed by pyrolysis in amixed CO₂/N₂ gas stream. It is likely that the chemical nature of thesurface of the material pyrolysed in N₂ only is different from thatpyrolysed in CO₂/N₂. It has been found that heating polymer-coatedsubstrates with acidification in a nitrogen atmosphere results inproducts having an increased carbon content compared with productsformed without acidification.

In accordance with this aspect of the invention, after final polymerdeposition, the coated pigment is isolated by filtration, washed anddried. Acidification of the dried material is accomplished by stirringthe coated substrate in a dilute, aqueous mineral acid solution for 30seconds to 2 hours, typically 1 to 45 minutes. The treated samples arefiltered, washed and dried prior to pyrolysis. Mineral acids which canbe used include sulfuric, nitric and phosphoric acids.

The carbon-coated pigment can be optionally coated with a wide varietyof inorganic and organic coloring agents or dyestuffs. Examples aredescribed, for instance, in U.S. Pat. Nos. 4,084,983; 4,755,229;4,968,351; and 6,436,538.

The carbon-coated pigment may, if desired, contain absorption pigments,which are water insoluble, transparent (i.e. substantially non-lightscattering) and which cannot be formed in situ from a water solublereactant(s) but which may be highly dispersed in water or water-alcoholcontaining anionic polymer. These include, for example, organic pigmentsin the following groups: azo compounds anthraquinones, perinones,perylenes, pyrroles such as diketopyrrolo pyrroles, quinacridones,thioindigos, dioxazines and phthalocyanines and their metal complexes.The absorption pigments, depending on their color intensity, are used ina concentration range of about 0.01% to about 30% based on the weight ofplaty substrate, preferably 0.1% to 10%.

As prepared, the carbon-coated materials may suffer from deteriorationupon prolonged exposure to UV radiation. The UV stability of thesematerials can be enhanced by incorporation of metal oxides or complexes.Specific examples of such metal species include cerium (III) oxide andcerium (IV) oxide.

Pigments having improved humidity resistance and weatherability can berealized by a metal oxide-coated mica pigment which has an aluminum oran aluminum-cerium combined with a hydrolyzed silane coupling agenttreated surface. Silane coupling agents such as aminosilanes,alkoxysilaned and aminoalkoxysilanes are useful. Commonly assigned U.S.Pat. No. 5,759,255 describes these coatings and is herein incorporatedby reference in its entirety.

Colors may be adjusted if desired by mixing combination pigments. Ingeneral, it is preferred to mix pigments of the same or similarreflection color, since reflection colors mix additively and colorintensity is reduced when very different reflection colors are mixed.The absorption pigment components mix subtractively, and the usualpigment blending procedures are followed.

The products of the present invention can be used in any applicationwhere pearlescent pigments have been used heretofore. Thus, the productsof this invention have an unlimited use in all types of automotive andindustrial paint applications, especially in the organic color coatingand inks field where deep color intensity is required. For example,these pigments can be used in mass tone or as styling agents to spraypaint all types of automotive and non-automotive vehicles. Forautomotive formulations, the weatherability treatment as described inU.S. Pat. No. 5,759,255 is particularly useful. Similarly, they can beused on all clay/formica/wood/glass/metal/enamel/ceramic and non-porousor porous surfaces. The pigments can be used in powder coatingcompositions. They can be incorporated into plastic articles geared forthe toy industry or the home. These pigments can be impregnated intofibers to impart new and esthetic coloring to clothes and carpeting.They can be used to improve the look of shoes, rubber and vinyl/marbleflooring, vinyl siding, and all other vinyl products. In addition, thesecolors can be used in all types of modeling hobbies.

The above-mentioned compositions in which the compositions of thisinvention are useful are well known to those of ordinary skill in theart. Examples include printing inks, nail enamels, lacquers,thermoplastic and thermosetting materials, natural resins and syntheticresins. Some non-limiting examples include polystyrene and its mixedpolymers, polyolefins, in particular, polyethylene and polypropylene,polyacrylic compounds, polyvinyl compounds, for example polyvinylchloride and polyvinyl acetate, polyesters and rubber, and alsofilaments made of viscose and cellulose ethers, cellulose esters,polyamides, polyurethanes, polyesters, for example polyglycolterephthalates, and polyacrylonitrile.

For a well-rounded introduction to a variety of pigment applications,see Temple C. Patton, editor, The Pigment Handbook, volume II,Applications and Markets, John Wiley and Sons, New York (1973). Inaddition, see for example, with regard to ink: R. H. Leach, editor, ThePrinting Ink Manual, Fourth Edition, Van Nostrand Reinhold(International) Co. Ltd., London (1988), particularly pages 282-591;with regard to paints: C. H. Hare, Protective Coatings, TechnologyPublishing Co., Pittsburgh (1994), particularly pages 63-288. Theforegoing references are hereby incorporated by reference herein fortheir teachings of ink, paint and plastic compositions, formulations andvehicles in which the compositions of this invention may be usedincluding amounts of colorants. For example, the pigment may be used ata level of 10 to 15% in an offset lithographic ink, with the remainderbeing a vehicle containing gelled and ungelled hydrocarbon resins, alkydresins, wax compounds and aliphatic solvent. The pigment may also beused, for example, at a level of 1 to 10% in an automotive paintformulation along with other pigments which may include titaniumdioxide, acrylic lattices, coalescing agents, water or solvents. Thepigment may also be used, for example, at a level of 20 to 30% in aplastic color concentrate in polyethylene.

In the cosmetic and personal care field, these pigments can be used inthe eye area and in all external and rinse-off applications. Thus, theycan be used in hair sprays, face powder, leg-makeup, insect repellentlotion, mascara cake/cream, nail enamel, nail enamel remover, perfumelotion, and shampoos of all types (gel or liquid). In addition, they canbe used in shaving cream (concentrate for aerosol, brushless,lathering), skin glosser stick, skin makeup, hair groom, eye shadow(liquid, pomade, powder, stick, pressed or cream), eye liner, colognestick, cologne, cologne emollient, bubble bath, body lotion(moisturizing, cleansing, analgesic, astringent), after shave lotion,after bath milk and sunscreen lotion.

In order to further illustrate the present invention, a number ofnon-limiting examples are set forth below. In these, as well asthroughout this specification and claims, all parts and percentages areby weight and all temperatures are in degrees centigrade, unlessotherwise indicated.

EXAMPLE 1

A 1% w/w solution of poly(diallyldimethyl ammonium chloride) (PDADMAC)in 0.1 M NaCl was prepared, and the pH adjusted to 9.5 using a 0.1 Mammonia solution. To 100 ml of this solution, 20 g of either TiO₂-coatedmica of 50 μm particle size, 20 μm platy mica or 100 μm TiO₂-coatedglass flakes was added, and the mixture stirred for 15 minutes at roomtemperature. After 15 minutes, the substrate was recovered by filtrationand washed with an excess of deionized water. This polymer treatmentconferred a positive charge on the substrate.

The substrate was then slurred in 100 ml of a 1% w/w solution ofpoly(sodium 4-styrene sulfonate) (PSS) in 0.1 M NaCl, adjusted to pH 9.5using 0.1 M ammonia for 15 minutes at room temperature and undercontinuous agitation. Following this treatment, the substrate wascollected by filtration and washed with deionized water to removeexcess, unattached polymer.

One treatment with PDADMAC followed by one treatment with PSS wasdefined as 1 treatment cycle. The treatment cycle was repeated and aftereach subsequent treatment cycle, a portion of the material was retainedfor pyrolysis and subsequent analysis. This allowed the depositionreaction to be examined as a function of the number of treatment cycles.

Samples were placed in a box furnace, and flowing nitrogen at 10liters/min was introduced into the furnace. Samples were heated to thetarget temperature over 2 hours and held at the target temperature for 3hours. The samples were then furnace cooled to ambient temperature, andremoved from the furnace. Elemental analyses were performed on thesamples after pyrolysis to determine the weight percentages of carbon.In addition, drawdown films were prepared to evaluate the influence ofthe carbon coating on the hiding power. As a reference point, a drawdownfilm was prepared using a pigment content comprised of 1% carbon blackand 99% the same substrate (effect pigment). Visual inspection revealedthat the carbon in the reference drawdown was more jet-black than thatproduced by precursor pyrolysis, which possessed more of a brown shade.

Table 1 details the carbon levels for three different substrates atvarious pyrolysis temperatures for five treatment cycles. TABLE 1 % C %C in TiO₂-Coated in TiO₂-coated % C in Platy Glass Flakes, mica, 50 μmMica, 2 μm 100 μm Untreated 0.01 0.016 N/A Polymer Coated 0.995 2.130.203 (unheated) 350° C., N₂ 0.722 1.41 0.142 375° C., N₂ 0.663 1.140.125 400° C., N₂ 0.556 0.929 0.093 425° C., N₂ 0.403 0.778 0.045 450°C., N₂ 0.157 0.437 0.016 500° C., N₂ 0.10 0.019 N/A

EXAMPLE 2

The polymer deposition procedure as carried out in Example 1 wasperformed on a TiO₂-coated mica having a particle size of approximately20 μm, a TiO₂-coated mica having a particle size of approximately 50 μmand TiO₂-coated borosilicate glass flakes having a particle sizeapproximately 100 μm. Following polymer deposition, pyrolysis wasperformed at various temperatures using a gaseous flow comprised of 1%CO₂ in N₂, as opposed to the pure nitrogen atmosphere used in Example 1above. Following this pyrolysis, elemental analyses were performed todetermine the carbon contents of the materials. These analyses aresummarized in Tables 2a, 2b and 2c. In addition, drawdown films wereprepared to evaluate the jet-black nature of the carbon coatingproduced. Inspection revealed that the carbon color was of jet-blackcolor similar to that of the reference drawdown film. Elemental analysisalso showed that more of the carbon was retained at elevatedtemperatures than with pyrolysis in nitrogen. TABLE 2 450° C. 500° C.550° C. Substrate % C % C % C TiO₂-coated 0.614 0.622 0.569 mica, 20 μmTiO₂-coated 0.539 0.520 0.539 mica, 50 μm TiO₂-coated 0.109 0.094 0.091Glass Flakes, 100 μm

EXAMPLE 3

Polymer deposition and subsequent pyrolysis to produce a carbon coatingwas performed on an iron oxide-coated mica using the procedure set forthin Example 1. Following multiple polymer deposition steps, pyrolysis at600° C. in CO₂/N₂ for two hours produced a dark brown sample that wasmagnetic. X-ray diffraction data were used to confirm that reduction ofthe Fe (III) had taken place to yield Fe₃O₄, a mixed Fe (II, III) oxide.Visual inspection of drawdown films prepared from these materialsindicates that the level of polymer deposition influences the degree ofiron reduction. Further, heating the substrate with no added polymer at600° C. in CO₂/N₂ for two hours also seems to promote a color change inthe material. The hiding power of the treated materials with some Fe₃O₄content is greater than the untreated material.

EXAMPLE 4

A 1% w/w solution of PDADMAC in 0.1 M NaCl was prepared, and the pHadjusted to about 9 using a 0.1 M ammonia solution. To 100 ml of thissolution, 20 g of a TiO₂-coated mica (Magnapearl®) 1000 productcommercially available from ENGELHARD) was added, and the mixturestirred for 15 minutes at room temperature. After 15 minutes, thesubstrate was recovered by filtration and washed with an excess ofdeionized water. The substrate was then slurred in 100 ml of a 1% w/wsolution of PSS in 0.1 M NaCl adjusted to pH about 9 using 0.1 M ammoniaand stirred for 15 minutes at room temperature. Following thistreatment, the substrate was collected by filtration and washed withdeionized water to remove excess, unattached polymer. The substrate wasthen subjected to repeat alternating treatments with PDADMAC and PSS toa total of five treatments with each polymer.

After the final filtration and washing, the sample was dried in air at90° C. overnight. The sample was then heated in a flowing gas stream ofcomposition 7.4% CO₂/92.6% N₂ to 600° C. in two hours and held at 600°C. for two hours, at which point the CO₂ flow was stopped. The samplewas then cooled in flowing nitrogen to room temperature. The finalproduct was a silver powder containing 0.73% w/w carbon.

The final product was incorporated into a nitrocellulose-based lacquerformulation, and drawn into a film. This was compared with a filmprepared using a formulation containing the same uncoated TiO₂-coatedmica and 1% w/w carbon black. The carbon-coated material with 0.73% w/wcarbon matched well with the formulation containing 1% w/w carbon blendintroduced as a blend.

EXAMPLE 5

A carbon coating was prepared according to Example 4, except thatMagnapearl® 1000 was replaced by Magnapearl® 4000 product (commerciallyavailable from ENGELHARD). The final product was a silver powder,containing 0.52% w/w carbon.

EXAMPLE 6

A carbon coating was prepared according to Example 4, except thatMagnapearl® 1000 was replaced by Firemist™ TiO₂-coated glass flake(commercially available from ENGELHARD). The final product was a silverpowder, containing 0.11% w/w carbon.

EXAMPLE 7

A carbon coating was prepared according to Example 4, except thatMagnapearl® 1000 was replaced by Mearlin® Hi-Lite Super Gold(commercially available from ENGELHARD). The final product is an intensegold powder, containing 0.78% w/w carbon.

The final product was incorporated into a nitrocellulose-based lacquerformulation, and drawn into a film. This was compared with a filmprepared using a formulation of the Mearlin® Hi-Lite Super Goldcontaining 0.75% w/w carbon black. The carbon-coated material with 0.78%w/w carbon has an intense gold interference color, and improved colorproperties at steep viewing angles compared with a physical blendcontaining 0.75% carbon black.

EXAMPLE 8

A carbon coating was prepared according to Example 4, except thatMagnapearl® 1000 was replaced by Mearlin® Hi-Lite Super Blue(commercially available from ENGELHARD). The final product is an intenseblue powder, containing 0.72% w/w carbon.

The final product was incorporated into a nitrocellulose-based lacquerformulation, and drawn into a film. This was compared with a filmprepared using a Mearlin®) Hi-Lite Super Blue formulation containing0.75% w/w carbon black. The carbon-coated material with 0.72% w/w carbonhas an intense blue interference color, and improved color properties atsteep viewing angles compared with a physical blend containing 0.75%carbon black.

EXAMPLE 9

A carbon coating was prepared according to Example 4, except thatMagnapearl® 1000 was replaced by Mearlin® Hi-Lite Super Red(commercially available from ENGELHARD). The final product is an intensered powder, containing 0.78% w/w carbon.

The final product was incorporated into a nitrocellulose-based lacquerformulation, and drawn into a film. This was compared with a filmprepared using a formulation containing the initial pigment combinedwith 0.75% w/w carbon black. The carbon-coated material with 0.78% w/wcarbon has an intense red interference color, and improved colorproperties at steep viewing angles compared with a physical blendcontaining 0.75% carbon black.

EXAMPLE 10

A carbon coating was prepared according to Example 4, except thatMagnapearl® 1000 was replaced by Mearlin® Hi-Lite Super Green(commercially available from ENGELHARD). The final product is an intensegreen powder, containing 0.56% w/w carbon.

The final product was incorporated into a nitrocellulose-based lacquerformulation, and drawn into a film. This was compared with a filmprepared using a formulation containing 1% w/w carbon black. Thecarbon-coated material with 0.56% w/w carbon has an intense greeninterference color, and improved color properties at steep viewingangles compared with a physical blend containing 1% carbon black.

EXAMPLE 11

A carbon coating was prepared on the TiO₂ coated mica according toExample 4, except that the gas composition for heating was 1% CO₂/99%N₂. The final product was a silver powder containing 0.73% w/w/ carbon.

EXAMPLE 12

A carbon coating was prepared according to Example 11, except thatMagnapearl® 1000 was replaced by Magnapearl® 2000 product (commerciallyavailable from ENGELHARD), and the substrate was subjected to only twotreatments with each polymer, applied in an alternating manner asPDADMAC, PSS, PDADMAC and PSS. The final product was dark silver incolor, and contained 0.68% w/w carbon of the total product. The nitrogencontent was 105 ppm of the total product, corresponding to 1.52% w/wnitrogen in the coating based upon carbon and nitrogen only.

EXAMPLE 13

A carbon coating was prepared according to Example 11, except thatMagnapearl® 1000 was replaced by Magnapearl® 3000 product (commerciallyavailable from ENGELHARD), and the substrate was subjected to alternatetreatments with PDADMAC and PSS. The final products were dark silver incolor, and their carbon contents (% w/w carbon) are 0.52, 0.83, 1.21,1.65 and 1.80 for 1 through 5 polymer treatment cycles, respectively.One polymer treatment cycle is defined as (PDADMAC+PSS).

EXAMPLE 14

A carbon-coated effect material using Mearlin® Hi-Lite Super Goldproduct was prepared according to Example 13, except that samples weretaken at the end of the second, fourth, sixth, eighth and tenth polymertreatment cycles. After filtration and washing, each sample was dried inair at 90° C. overnight. The samples were then heated in a flowing gasstream containing 7.4% CO₂/92.6% N₂ to 600° C. in two hours and held at600° C. for two hours, at which point the CO₂ flow was stopped. Thesamples were then cooled in flowing nitrogen to room temperature.

The carbon content of each sample were determined by elemental analysesand the results are summarized in the following Table, where nrepresents the number of (PDADMAC+PSS) polymer treatment cycles. n 2 4 68 10 % C w/w 0.36 0.76 1.17 1.59 2.08UV/Visible spectroscopy was performed on these samples and the influenceof carbon content on the spectra was examined. FIG. 1 shows a plot ofthe intensity of the peak at approximately 425 nm as a function ofcarbon level. FIG. 2 shows a plot of spectral peak position as afunction of carbon content.

EXAMPLE 15

A carbon-coated effect material was prepared by slurring 20 g ofMagnapearl® 4000 in 100 ml of 0.1 M NaCl, and adjusting the pH to about9. To this was added 0.135 g of 20% w/w aqueous PDADMAC, and the mixturestirred for 15 minutes. Then without any intermediate filtration orwashing, 0.0403 g of PSS was added and the mixture stirred for 15minutes. This procedure was repeated with the PDADMAC and PSS addedalternately with 15 minutes between subsequent additions. After 5 totaladditions of each polymer, the substrate was collected by filtration andwashed with deionized water. After filtration and washing, the samplewas dried in air at 90° C. overnight. The sample was then heated in aflowing gas stream containing 7.4% CO₂/92.6% N₂ to 600° C. in two hoursand held at 600° C. for two hours, at which point the CO₂ flow wasstopped. The sample was then cooled in flowing nitrogen to roomtemperature. The final product was a silver powder containing 0.31% w/wcarbon.

EXAMPLE 16

A carbon coating was prepared according to Example 15, except that theMagnapearl® 4000 was replaced by Mearlin® Hi-Lite Super Gold product,and 1% w/w solutions of each polymer in 0.1 M NaCl were employed foreach polymer addition. For the PDAMAC, 3.42 g of this 1% solution wasadded per 20 g of substrate, and 5.38 g 1% w/w PSS solution was addedper 20 g of substrate. There was no filtration or washing betweensuccessive polymer deposition steps. After ten (PDADMAC+PSS) alternatingpolymer depositions, the deposition process was stopped, and thesubstrate collected by filtration, washed with deionized water and thesample was dried in air at 90° C. overnight. The sample was then heatedin a flowing gas stream containing 7.4% CO₂ and 92.6% N₂ to 600° C. intwo hours and held at 600° C. for two hours, at which point the CO₂ flowwas stopped. The sample was then cooled in flowing nitrogen to roomtemperature. The final product was an intense gold powder containing0.84% w/w carbon. The UV/Vis spectrum of this material is shown in FIG.3, in addition to that of the unmodified Mearlin Hi-Lite Super Gold(control).

EXAMPLE 17

A carbon coated effect material was prepared according to Example 16,except that the Mearlin® Hi-Lite Super Gold was replaced by Lumina®Turquoise product. Following pyrolysis, the powdered product was anintense turquoise color and had a carbon content of 0.66% w/w. TheUV-visible spectrum of this material is shown in FIG. 4, which alsoshows the spectrum of a physical blend of carbon black and unmodifiedLumina® Turquoise at a carbon level of 0.75% w/w. The addition of carbonto Lumina® Turquoise either by coating or physical blending produces twonew absorption bands having similar positions. However, the bandintensity, F(R), of the carbon-coated Lumina® Turquoise is much strongerthan that of the mechanically blended carbon black/Lumina® Turquoise.This shows that carbon-coated effect materials display enhanced colorstrength compared with those obtained by mechanically blending with anequivalent of carbon black.

EXAMPLE 18

The procedure of Example 17 was repeated to different carbon contents byvarying the number of (PDADMAC+PSS) treatment cycles from 2 to 10. TheUV spectra of these products is plotted in FIG. 5 and the intensity ofthe peak at about 600 nm as a function of carbon level is set forth inFIG. 6. In addition, the intensity difference between the UV/Visfeatures at approximately 600 nm and 490 nm was plotted with varyingcarbon content as shown in FIG. 7. The band intensity increases as thecarbon content increases from 0.24 to 0.53% and then levels off when thecarbon content further increases from 0.53 to 0.86%. This indicates apreferred carbon level for optical enhancement, beyond which no apparentadvantage is gained, and additional carbon may even be detrimental interms of color properties.

FIG. 8 shows the change of band width (at half peak height) with thecarbon content for carbon-coated Lumina® Turquoise and indicates that asthe carbon content increases, so does the band width. FIG. 9 gives theplot of band position with the carbon content.

EXAMPLE 19

A carbon coated effect material was prepared according to Example 16,except that the Mearlin® Hi-Lite Super Gold was replaced by Mearlin®Hi-Lite Super Green product. Following pyrolysis, the powdered productwas an intense green color with a carbon content of 0.75% w/w. TheUV-visible spectrum of this material is shown in FIG. 10, which alsoshows the spectrum of the unmodified Mearlin® Hi-Lite Super Green(control).

EXAMPLE 20

A carbon coated effect material was prepared according to Example 16,except that the Mearlin® Hi-Lite Super Gold was replaced by Mearlin®Hi-Lite Super Blue product. Following pyrolysis, the powdered productwas an intense blue color and had a carbon content of 0.77% w/w. TheUV-visible spectrum of this material and that of the unmodified Mearlin®Hi-Lite Super Blue are shown in FIG. 11 (control).

EXAMPLE 21

The carbon coated material produced in Example 20 was further treatedwith a weatherability treatment in accordance with commonly assignedU.S. Pat. No. 5,759,255 incorporated herein by reference.

EXAMPLE 22

The carbon coated effect material of Example 20 was incorporated into apowder eye shadow of the following formulation: Ingredients wt partsTalc 19.4 Mearlmica ® SVA product 15.0 Magnesium Myristate 5.0 Silica2.0 Preservatives 0.5 Product of example 20 50.0 Octyl Palmitate 7.0Isostearyl Neopentanoate 1.0 BHT 0.1For comparative purposes, the formulation was repeated where the productof Example 20 was replaced with a physical blend of Hi Lite Super Blueand 0.25% carbon black pigment. When wiped off the skin, the blendedpigments leaves a residue behind, while the carbon-coated pigment doesnot.

EXAMPLE 23

The carbon coated effect material of Example 20 was incorporated into anail enamel of the following formulation: Ingredients wt partsSuspending lacquer SLF-2 82.0 Product of Example 20 3.0 Lacquer 127P10.5 Polynex B-75 2.5 Ethyl Acetate 2.0

EXAMPLE 24

A charge of 1.0 wt % of the product of Example 17 was added topolypropylene and dispersed therein and injected molded into a flatplaque.

EXAMPLE 25

The carbon coated pigment of Example 17 was incorporated into a waterbased paint composition at a pigment/paint ratio of 0.13. The paint wassprayed onto a primed steel panel to about 15-20 microns. This base coatwas allowed to flash for at least 10 minutes, and then baked at 85° C.for 6.5 minutes before cooling. A clearcoat was then applied to athickness of 40-45 microns and the resulting panel was baked at 140° C.for 30 minutes.

EXAMPLE 26

The carbon-coated effect material of Example 17 was sprayed at 3.5 wt %loading in a polyester TGIC power coating using a corona gun over a RAL9005 black powder sprayed base. For comparative purposes, the powdercoating process was repeated except that the effect material wasreplaced by a blend of Lumina® Turquoise product and carbon black. Thecoating using the carbon-coated effect pigment has higher chroma and acleaner color compared to the coating using the mixture. Also, thecoating using the carbon-coated effect pigment retained the intenseturquoise color at more diffuse angles while the coating using themixture became washed out by a blue-gray haze.

EXAMPLE 27

A carbon-coated effect material was prepared as described in Example 16,except that the effect pigment used was Lumina® Pearl Radiance 130DSilver. The carbon content of the product was 0.75% w/w, and thenitrogen content was 215 ppm, corresponding to 2.79% w/w of nitrogen inthe coating based upon carbon and nitrogen only.

EXAMPLE 28

The pigment of this invention can be formulated into a powder eye shadowby thoroughly blending and dispersing the following materials:Ingredients wt parts Mearltalc TCA ® (Talc) 18 Mearlmica ® SVA (Mica) 20Magnesium Myristate 5 Silica 2 Cloisonné ® Red 424C (red TiO₂-coatedmica) 20 Cloisonné ® Violet 525C (violet TiO₂-coated mica) 13Cloisonné ® Nu-Antique Blue 626CB (TiO₂-coated 2 mica/iron oxide-coatedmica) Cloisonné ® Cerise Flambé 550Z (iron oxide-coated mica) 2Preservatives & Antioxidant q.s.

Then 7 parts of octyl palmitate and 1 part of isostearyl neopentanoateare heated and mixed until uniform, at which time the resulting mixtureis sprayed into the dispersion and the blending continued. The blendedmaterial is pulverized and then 5 parts of Cloisonne® Red 424C and 5parts of the pigment of this invention added and mixed until a uniformpowder eye shadow is obtained.

EXAMPLE 29

The pigment can be formulated into a lipstick by placing the followingamounts of the listed ingredients into a heated vessel and raising thetemperature to 85±3° C.: Ingredients wt parts Candelilla Wax 2.75Carnauba Wax 1.25 Beeswax 1.00 Ceresine Wax 5.90 Ozokerite Wax 6.75Microcrystalline Wax 1.40 Oleyl Alcohol 3.00 Isostearyl Palmitate 7.50Isostearyl Isostearate 5.00 Caprylic/Capric Triglyceride 5.00Bis-Diglycerylpolyalcohol Adipate 2.00 Acetylated Lanolin Alcohol 2.50Sorbitan Tristearate 2.00 Aloe Vera 1.00 Castor Oil 37.50 Red 6 Lake0.25 Tocopheryl Acetate 0.20 Phenoxyethanol, Isopropylparaben, andbutylparaben 1.00 Antioxidant q.s.

A mixture of 13 parts of the pigment of this invention and 1 part ofkaolin are added and mixed until all of the pigment is well dispersed.Fragrance is added as desired and mixed with stirring. The resultingmixture is poured into molds at 75±5° C., allowed to cool and flamedinto lipsticks.

EXAMPLE 30

Carbon coated effect materials were prepared according to Example 7except that the effect pigment slurry and polymer solutions were used atpH 7, and the polymer-coated materials were pyrolysed at 600° C. in agas stream comprising 1% CO₂/99% N₂. Following pyrolysis, the carboncontents (% w/w carbon) were 0.16, 0.30, 0.48, 0.66 and 0.86 for 1through 5 polymer treatments respectively.

EXAMPLE 31

Carbon coated effect materials were prepared according to Example 30,except that the polymer-coated materials were pyrolysed at 650° C. in agas stream comprising 1% CO₂/99% N₂. Following pyrolysis, the carboncontents (% w/w carbon) were 0.09, 0.24, 0.44, 0.63 and 0.80 for 1through 5 polymer treatments respectively.

EXAMPLE 32

Carbon coated effect materials were prepared according to Example 30except that the effect pigment slurry and polymer solutions were used atpH 5. Following pyrolysis, the carbon contents (% w/w carbon) were 0.16,0.32, 0.49, 0.70 and 0.90 for 1 through 5 polymer treatmentsrespectively.

EXAMPLE 33

Carbon coated effect materials were prepared according to Example 32except that the polymer-coated materials were pyrolysed at 650° C. in agas stream comprising 1% CO₂/99% N₂. Following pyrolysis, the carboncontents (% w/w carbon) were 0.10, 0.24, 0.41, 0.60 and 0.81 for 1through 5 polymer treatments respectively.

EXAMPLE 34

A carbon-coated Mearlin® Hi-Lite Super Gold was prepared according toExample 16 except that polymer deposition was limited to fivealternating polymer deposition cycles, where one cycle is defined as(PDADMAC+PSS). After pyrolysis, the final product contained 0.41% w/wcarbon.

EXAMPLE 35

4.44 g of the carbon-coated product from Example 34 was slurried in 0.1M NaCl aqueous solution to a total volume of 100 ml, and the pH adjustedto ˜9. To this was added 0.76 g of a solution comprising 1% w/w ofPDADMAC in 0.1 M aqueous NaCl, and the mixture stirred for 5 minutes.1.19 g of a solution comprising 1% w/w of PSS in 0.1 M aqueous NaCl wasadded to this mixture with no intermediate filtration or washing, andthe mixture stirred at room temperature for 5 minutes. The samequantities of PDADMAC and PSS were added alternately with 5 minutesinbetween subsequent additions. After 5 total additions of each polymer,the substrate was collected by filtration and washed with deionizedwater. After filtration and washing, the sample was dried in air at 90°C. overnight. The sample was then heated in a flowing gas stream ofcomposition 1% CO₂/99% N₂ to 600° C. in two hours and held at 600° C.for two hours, at which point the CO₂ flow was stopped. The sample wasthen cooled in flowing nitrogen to room temperature. The final productwas an intense gold powder containing 1.78% w/w carbon.

EXAMPLE 36

110 g of commercially available TiO₂ coated mica (Lumina Red Blue,9B30D) was slurried in 990 ml of 0.01 M NaCl, and the slurry maintainedunder constant agitation. To this slurry was added 10.0 g of 1% w/waqueous PDADMAC (average molecular weight 100,000-200,000) in 0.01 MNaCl, and the mixture stirred for 5 minutes. Then without anyintermediate filtration or washing, 20.0 g of 1% w/w aqueous PSS(average molecular weight 70,000) in 0.01 M NaCl was added and themixture stirred for 5 minutes. Measured amounts of PDADMAC and PSSpolymers were added in an alternating manner until a total of eightadditions of each polymer had been completed. The amounts of eachpolymer used per addition as a 1% w/w polymer in 0.01 M NaCl aredetailed in the table below: Polymer Deposition Amount of PDADMAC Amountof PSS Per Number per deposition/g Deposition/g 1 10.0 20.0 2 12.5 22.53 15.0 22.5 4 15.0 22.5 5 17.5 25.0 6 20.0 27.5 7 20.0 30.0 8 22.5 30.0After eight alternate additions of each polymer solution, the solidproduct was recovered by filtration, washed with excess deionized water,and dried overnight at 90° C. After drying, the solid was placed in abox furnace, and flowing nitrogen containing 1% CO₂ was introduced intothe furnace. The solid sample was heated to 600° C. in two hours, andthen held at that temperature for 2 hours. The sample was then furnacecooled to ambient temperature in flowing nitrogen, and removed from thefurnace. Elemental analysis performed on the sample after pyrolysisindicated a carbon content of 0.66% w/w. The material was an intensered-blue color after pyrolysis.

EXAMPLE 37

11 g of commercially available TiO₂ coated mica (Lumina Red Blue, 9B30D)was slurried in 99 ml of 0.01 M NaCl, and the pH adjusted toapproximately 9. The slurry was maintained under constant agitation. Tothis slurry was added 2.0 g of 1% w/w aqueous PDADMAC (average molecularweight 400,000-500,000) in 0.1 M NaCl, and the mixture stirred for 5minutes. Then without any intermediate filtration or washing, 3.0 g of1% w/w aqueous PSS (average molecular weight 70,000) in 0.1 M NaCl wasadded and the mixture stirred for 5 minutes. Measured amounts of PDADMACand PSS polymers were added in an alternating manner until a total offour additions of each polymer had been completed. The amounts of eachpolymer used per addition as a 1% w/w polymer in 0.1 M NaCl are detailedin the table below: Polymer Deposition Amount of PDADMAC Amount of PSSPer Number per deposition/g Deposition/g 1 2.0 3.0 2 2.0 3.5 3 2.0 3.754 2.25 4.25After four alternate additions of each polymer solution, the solidproduct was recovered by filtration, washed with excess deionized water,and dried overnight at 90° C. After drying, the solid was placed in abox furnace, and flowing nitrogen containing 1% CO₂ was introduced intothe furnace. The solid sample was heated to 600° C. in two hours, andthen held at that temperature for 2 hours. The sample was then furnacecooled to ambient temperature in flowing nitrogen, and removed from thefurnace. Elemental analysis performed on the sample after pyrolysisindicated a carbon content of 0.46% w/w. The material was an intensered-blue color after pyrolysis.

EXAMPLE 38

A material was prepared as described in Example 37, except that thepolymer deposition was continued until six depositions of each of thepolymers, PDADMAC and PSS, had been applied in an alternating manner.The amounts of each polymer used per addition as a 1% w/w polymer in 0.1M NaCl are detailed in the table below: Polymer Deposition Amount ofPDADMAC Amount of PSS Per Number per deposition/g Deposition/g 1 2.0 3.02 2.0 3.5 3 2.0 3.75 4 2.25 4.25 5 2.75 4.5 6 3.0 5.0After six alternate additions of each polymer solution, the solidproduct was recovered by filtration, washed with excess deionized water,and dried overnight at 90° C. After drying, the solid was placed in abox furnace, and flowing nitrogen containing 1% CO₂ was introduced intothe furnace. The solid sample was heated to 600° C. in two hours, andthen held at that temperature for 2 hours. The sample was then furnacecooled to ambient temperature in flowing nitrogen, and removed from thefurnace. Elemental analysis performed on the sample after pyrolysisindicated a carbon content of 0.79% w/w. The material was an intensered-blue color after pyrolysis.

EXAMPLE 39

10 g of commercially available TiO₂ coated mica (Lumina Red Blue, 9B30D)was slurried in 90 ml of 0.1 M NaCl, and the pH adjusted toapproximately 9. The slurry was maintained under constant agitation. Tothis slurry was added 2.52 g of 1% w/w aqueous PDADMAC (averagemolecular weight 100,000-200,000) in 0.1 M NaCl at pH 9, and the mixturestirred for 5 minutes. Then without any intermediate filtration orwashing, 3.22 g of 1% w/w aqueous PSS (average molecular weight 70,000)in 0.1 M NaCl at pH 9 was added and the mixture stirred for 5 minutes.Repeat additions of 2.52 g PDADMAC and 3.22 g PSS polymers were added inan alternating manner until a total of six additions of each polymer hadbeen completed.

After six alternate additions of each polymer solution, the solidproduct was recovered by filtration, washed with excess deionized water,and dried overnight at 90° C. After drying, the solid was placed in abox furnace, and flowing nitrogen containing 1% CO₂ was introduced intothe furnace. The solid sample was heated to 600° C. in two hours, andthen held at that temperature for 2 hours. The sample was then furnacecooled to ambient temperature in flowing nitrogen, and removed from thefurnace. Elemental analysis performed on the sample after pyrolysisindicated a carbon content of 0.77% w/w. The material was an intensered-blue color after pyrolysis.

EXAMPLE 40

UV-Visible spectroscopy was used to investigate the color intensity,F(R), of Examples 36-39. These results are shown in FIG. 12.

FIG. 12 demonstrates that high color intensity can be obtained bycarefully controlling polymer deposition prior to pyrolysis, and thatcolor intensity is not solely a function of carbon content.

EXAMPLE 41

Polymer deposition was performed on Lumina Red Blue as in Example 39except the polymer deposition was continued until five depositions ofeach of the polymers, PDADMAC and PSS, had been applied in analternating manner. Aliquots were taken after every cycle (PDADMAC &PSS). After filtration and washing, each sample was dried in air at 90°,and then slurried in 1% w/w aqueous sulfuric acid at a pH ofapproximately 2. After 15 minutes contact time, the samples werefiltered, washed, and dried. Pyrolysis was then performed in flowingnitrogen by heating to 600° C. in two hours, holding at 600° C. for twohours, and cooling to room temperature. The samples were an intense bluecolor. Elemental analyses revealed carbon contents of 0.12, 0.25, 0.38,0.47, and 0.62% w/w carbon for 1 through 5 polymer cycles respectively.

EXAMPLE 42

20 g of commercially available TiO₂-coated mica (Lumina Turquoise) wasadded to a solution comprising 2 g of concentrated H₃PO₄ and 198 gdeionized water. After stirring for 15 minutes at room temperature, thesubstrate was collected by filtration, washed and dried at 90° C.

The substrate was then added to 100 ml of 0.1 M NaCl. To this was added6.44 g of 1% w/w aqueous PSS in 0.1 M NaCl, and the mixture stirred for5 minutes. Then without any intermediate filtration or washing, 5.05 gof 1% w/w aqueous PDADMAC in 0.1 M NaCl was added and the mixturestirred for 5 minutes Alternate polymer depositions of PSS and PDADMACwere applied with no intermediate filtration or washing at intervals offive minutes until a total of eight treatments with each polymer hadbeen achieved. The substrate composition is then described asTCM+(PSS+PDADMAC)₈. The substrate was then filtered, washed with anexcess of deionized water, and dried at 90° C.

The substrate was then heated in a box furnace in flowing nitrogen fromroom temperature to 600° C. in two hours, and the temperature held at600° C. for two hours in flowing nitrogen. The sample was then cooled toroom temperature in flowing nitrogen. The powdered sample was an intenseturquoise color. Elemental analysis gave a carbon content of 0.97%carbon w/w.

EXAMPLE 43

10 g of cationic starch Cellquat® H-100 (National Starch and Chemical)was dissolved in 990 g deionized water. To 200 ml of this solution wasadded 20 g of commercially available TiO₂-coated mica (Lumina Turquoise9T30D), and the mixture stirred at room temperature for 5 minutes. After5 minutes, the substrate was recovered by filtration, and washed with anexcess of deionized water.

The substrate was then slurried in a solution comprising 2 g ofpoly(sodium 4-styrene sulfonate) (PSS) dissolved in 200 g of 0.1 M NaCl.The mixture was stirred at room temperature for 5 minutes, and thesubstrate collected by filtration, and washed with an excess ofdeionized water.

Alternating H-100 and PSS treatments were then repeated until a total of5 depositions of each of the H-100 and PSS had been applied. Aliquotswere taken after one, three and five H-100 PSS treatments. Samples werethen dried at 90° C. in air. After drying, samples were placed in a boxfurnace, and flowing nitrogen containing 1% CO₂ was introduced into thefurnace. Samples were heated to 600° C. in two hours, and held at 600°C. for 2 hours. The samples were then furnace cooled to ambienttemperature in flowing nitrogen, and removed from the furnace. Sampleswere a turquoise color after pyrolysis. Elemental analyses wereperformed on the samples before and after pyrolysis to determine theweight percentages of carbon. Elemental results gave carbon contents of0.14, 0.17 and 0.42% carbon w/w for one, three and five H-100/PSStreatments respectively.

EXAMPLE 44

1 g of 4-aminobenzoic acid (para benzoic acid, PABA) was dissolved in 99g of deionized water by heating to approximately 45° C. until a clearliquid was obtained. To 25 g of this solution was added 5 g ofcarbon-coated Lumina Red Blue prepared as described in Example 39 usingseven cycles of continuous (PDADMAC+PSS) polymer addition, followed bypyrolysis at 600° C. in 1% CO₂/99% N₂. The carbon content of thissubstrate prior to reaction with PABA was 0.71% w/w.

After stirring the carbon-coated substrate in the PABA solution for 5minutes, the substrate was collected by filtration, washed with anexcess of deionized water and dried at 90° C. Elemental analysisrevealed that the carbon content following reaction with PABA was 1.05%carbon w/w.

EXAMPLE 45

20 g of commercially available TiO₂ coated mica (Lumina Turquoise 9T30D)was slurried in a solution comprising 2.0 g of 20 w/w aqueous PDADMAC in72 g of 0.1 M aqueous NaCl at pH 7. After stirring at room temperaturefor 5 minutes, the solid was recovered by filtration, and washed withdeionized water. The solid was then added to a solution containing 1.0 gof 40% w/w polyacrylic acid (PAA, average molecular weight 30,000) in 72g of 0.1 M aqueous NaCl at pH 7. The pH of the slurry was then increasedto ˜9.4. After stirring for 5 minutes at room temperature, the solid wasrecovered by filtration, and washed with deionized water. Alternatetreatments of the solid with PDADMAC and PAA were repeated in ananalogous manner until a total of four alternating treatments with eachpolymer had been applied. Pyrolysis was performed as detailed in Example39. The carbon content of the material after pyrolysis was determined byelemental analysis to be 0.18% w/w.

EXAMPLE 46

A 1% w/w solution of polyethylene imine, (PEI, average molecular weight750,000) in 0.1 M NaC1 was prepared, and the pH adjusted to about 6. To100 ml of this solution, 10 g of a commercially available TiO₂-coatedmica (Lumina Red Blue) was added, and the mixture stirred for 5 minutesat room temperature. After 5 minutes, the substrate was recovered byfiltration and washed with deionized water that had been adjusted topH˜6. The substrate was then slurried in 100 ml of a 1% w/w solution ofPSS in 0.1 M NaCl and stirred for 5 minutes at room temperature.Following this treatment, the substrate was collected by filtration andwashed with deionized water that had been adjusted to pH ˜6. Thesubstrate was then subjected to repeat alternating treatments with PEIand PSS to a total of six treatments with each polymer. Aliquots weretaken after four, five and six polymer deposition cycles.

After the final filtration and washing, the sample was dried in air at90° C. overnight. Pyrolysis was performed as detailed in Example 39. Thecarbon contents after pyrolysis for samples prepared using four, fiveand six polymer deposition cycles were 0.45% ,0.54% and 0.65%respectively.

EXAMPLE 47

100 g of commercially available TiO₂ coated mica (Lumina Turquoise,9T30D) was dispersed in 666 g of deionized water. Cerium and aluminumwere deposited on the surface of the substrate according to a processdescribed in U.S. Pat. No. 5,759,255. Aqueous cerium and aluminum saltswere added in amounts appropriate to achieve a 0.4% w/w Ce loading and a0.29w/w % Al loading based on the total weight of solid product.Following cerium/aluminum deposition, the solid was recovered byfiltration, washed with deionized water and dried at 120° C.

20 g of this material was then dispersed in 100 ml of 0.1 M NaCl, andthe pH adjusted to approximately 9. The slurry was maintained underconstant agitation. To this slurry was added 5.05 g of 1% w/w aqueousPDADMAC at pH ˜9 (average molecular weight 100,000-200,000) in 0.1 MNaCl, and the mixture stirred for 5 minutes. Then without anyintermediate filtration or washing, 6.44 g of 1% w/w aqueous PSS at pH˜9 (average molecular weight 70,000) in 0.1 M NaCl was added and themixture stirred for 5 minutes. Repeat additions of these polymer amountswere made by alternating PDADMAC and PSS polymers until a total of sixadditions of each polymer had been completed.

After six alternate additions of each polymer solution, the solidproduct was recovered by filtration, washed with excess deionized water,and dried overnight at 90° C. After drying, the solid was placed in abox furnace, and flowing nitrogen containing 1% CO₂ was introduced intothe furnace. The solid sample was heated to 600° C. in two hours, andthen held at that temperature for 2 hours. The sample was then furnacecooled to ambient temperature in flowing nitrogen, and removed from thefurnace. The material was an intense turquoise color after pyrolysis.Elemental analysis performed on the sample after pyrolysis indicated acarbon content of 0.81% w/w. The material displayed enhanced UVstability compared with a carbon-coated sample that had no ceriumtreatment.

EXAMPLE 48

A material was prepared as described in Example 47 except that theaqueous deposition of 0.4% w/w Ce loading and a 0.29w/w % Al loading waschanged to only 0.34% w/w Ce. The material was an intense turquoisecolor after pyrolysis. Elemental analysis performed on the sample afterpyrolysis indicated a carbon content of 0.86% w/w. XPS on thecarbon-coated sample showed a total surface cerium content of 1.25 atompercent, comprised of 0.98% Ce³⁺ and 0.27% Ce⁴⁺(Ce⁴⁺/Ce³⁺=0.28).

EXAMPLE 49

25 g of commercially available TiO₂ coated mica (Lumina Turquoise,9T30D) was dispersed in 167 g of deionized water. Cerium was depositedon the surface of the substrate according to a process described in U.S.Pat. No. 5,759,255 in an amount corresponding to a 0.34% w/w Ce loadingbased on the total weight of solid product.

Following cerium deposition, the heat source was removed, and polymeraddition was undertaken with no intermediate filtration or washing. ThepH of the slurry was adjusted to ˜9, and 6.33 g of 1% w/w aqueousPDADMAC (average molecular weight 100,000-200,000) in 0.1 M NaCl at pH˜9 was added, and the mixture stirred for 5 minutes. Then without anyintermediate filtration or washing, 8.05 g of 1% w/w aqueous PSS(average molecular weight 70,000) in 0.1 M NaCl at pH ˜9 was added andthe mixture stirred for 5 minutes. Repeat additions of these polymeramounts were made by alternating PDADMAC and PSS polymers until a totalof six additions of each polymer had been completed.

After six alternate additions of each polymer solution, the solidproduct was recovered by filtration, washed with excess deionized water,and dried overnight at 90° C. After drying, the solid was placed in abox furnace, and flowing nitrogen containing 1% CO₂ was introduced intothe furnace. The solid sample was heated to 600° C. in two hours, andthen held at that temperature for 2 hours. The sample was then furnacecooled to ambient temperature in flowing nitrogen, and removed from thefurnace. The material was an intense turquoise color after pyrolysis.Elemental analysis performed on the sample after pyrolysis indicated acarbon content of 0.75% w/w. XPS on the carbon-coated sample showed atotal surface cerium content of 1.6 atom percent, comprised of 0.7% Ce³⁺and 0.9% Ce⁴⁺(Ce⁴⁺/Ce³⁺=1.3).

EXAMPLE 50

A material was prepared as described in Example 49 except that thecerium deposition was performed at ambient temperature. The materialafter pyrolysis was an intense turquoise color, and contained 0.77% w/wcarbon. XPS on the carbon-coated sample showed a total surface ceriumcontent of 1.9 atom percent, comprised of 0.7% Ce³⁺ and 1.2% Ce⁴⁺(Ce⁴⁺/Ce³⁺=1.7).

EXAMPLE 51

25 g of commercially available TiO₂ coated mica (Lumina Turquoise,9T30D) was dispersed in 167 g of deionized water, and the pH adjusted toapproximately 3 with 1:1 hydrochloric acid. 0.42 g of cerium (IV)sulfate hydrate complex with sulfuric acid, Ce(SO₄)₂.H₂O.H₂SO₄, wasadded and stirred for approximately 15 minutes at room temperature. ThepH was then slowly increased to approximately 6.5 by the addition of3.5% NaOH solution, and the mixture stirred for 30 minutes.

Polymer addition was then undertaken with no intermediate filtration orwashing. The pH of the slurry was adjusted to ˜9, and 6.33 g of 1% w/waqueous PDADMAC (average molecular weight 100,000-200,000) in 0.1 M NaClat pH ˜9 was added, and the mixture stirred for 5 minutes. Then withoutany intermediate filtration or washing, 8.05 g of 1% w/w aqueous PSS(average molecular weight 70,000) in 0.1 M NaCl at pH˜9 was added andthe mixture stirred for 5 minutes. Repeat additions of these polymeramounts were made by alternating PDADMAC and PSS polymers until a totalof six additions of each polymer had been completed.

After six alternate additions of each polymer solution, the solidproduct was recovered by filtration, washed with excess deionized water,and dried overnight at 90° C. After drying, the solid was placed in abox furnace, and flowing nitrogen containing 1% CO₂ was introduced intothe. furnace. The solid sample was heated to 600° C. in two hours, andthen held at that temperature for 2 hours. The sample was then furnacecooled to ambient temperature in flowing nitrogen, and removed from thefurnace. The material after pyrolysis was an intense turquoise color,and contained 0.74% w/w carbon. XPS on the carbon-coated sample showed atotal surface cerium content of 0.7 atom percent, comprised of 0.7%Ce³⁺; Ce⁴⁺ was not detected.

Various changes and modifications can be made in the process andproducts of the present invention without departing from the spirit andscope thereof. The embodiments described and illustrated herein were forthe purpose of further illustrating the invention but were not intendedto limit it.

1-17. (canceled)
 18. A method of forming a carbon-coated high lusterplaty pigment comprising coating a platy pigment substrate with at leastone carbon-containing ionic species or alternating layers of oppositelycharged carbon-containing ionic species, treating the coating togenerate a carbon coating on said substrate.
 19. The method of claim 18wherein the substrate is an effect pigment and the carbon-containingionic species is a cationic or anionic polymer.
 20. The method of claim19 comprising coating the substrate with at least one alternatingsequence of cationic and anionic polymers.
 21. The method of claim 20wherein the substrate is coated with at least two alternating sequencesof cationic and anionic polymers.
 22. The method of claim 20 in whichthe substrate is coated with at least one alternating sequence ofpolydiallyldimethyl ammonium chloride and poly (sodium 4-styrenesulfonate).
 23. The method of claim 18 in which the organic coating iscontacted with a gas at elevated temperature to convert said organiccoating to said carbon coating.
 24. The method of claim 23 in which saidgas is an inert gas at a temperature of at least about 300° C.
 25. Themethod of claim 24 wherein the inert gas is nitrogen.
 26. The method ofclaim 23 wherein the gas is a carbon dioxide-containing inert gas. 27.The method of claim 23 comprising contacting the organic coatedsubstrate with an acid prior to being thermally treated.
 28. The methodof claim 27 wherein said acid is a mineral acid.
 29. The method of claim28 wherein said mineral acid is sulfuric acid.
 30. The method of claim27 in which said organic coating is contacted with an inert gas at atemperature of at least about 300° C.
 31. The method of claim 18 whereinsaid platy substrate is a Fe₂O₃-coated platy substrate and saidcarbon-coated pigment contains divalent iron, trivalent iron, ormixtures thereof.
 32. The method of claim 31 wherein said carbon-coatedpigment contains Fe₃O₄.
 33. The method of claim 31 wherein saidFe₂O₃-coated platy substrate comprises Fe₂O₃ and TiO₂ coatings on mica.34-42. (canceled)